VON BAER AND RISE OF EMBRYOLOGY. 101 



spot or cicatricula. He also corrected Aristotle, Fabricius and his 

 other predecessors in many particulars. 



Harvey's greatest predecessor in this field, Fabricius, was also his 

 teacher. When, in search of the best training in medicine, Harvey 

 wended his way from England to Italy, in Padua, he came under 

 Fabricius as one of his teachers. In 1G00, Fabricius published the 

 earliest illustrations on the development of animals, and, again, in 

 1625, six years after his death, appeared his illustrated treatise on the 

 development of the chickjf Altogether his figures show develop- 

 mental stages of the cow, sheep, pig, galeus, serpent, rat and chick. 

 The value of his work may be easily overestimated by a casual ex- 

 amination of the plates. 



Harvey's own treatise was not illustrated. With that singular in- 

 dependence of mind which he showed in all his work, the vision of 

 the pupil was not hampered by the authority of his teacher, and, trust- 

 ing only to his own sure observation and reason, he described the 

 stages of development as he saw them in the egg, and placed his 

 own construction on the facts. 



One of the earliest things to arrest his attention in the chick was 

 a pulsating point, the heart, and, from this observation, he supposed 

 that the heart and blood were the first formations. He says : " But 

 as soon as the egg, under the influence of the gentle warmth of the 

 incubating hen, or of warmth derived from another source, begins to 

 pullulate, this spot forthwith dilates, and expands like the pupil of 

 the eye, and from thence, as the grand center of the egg, the latent 

 plastic force breaks forth and germinates. This first commencement 

 of the chick, however, so far as I am aware, has not yet been observed 

 by any one." 



It is to be understood, however, that his descriptive part is rela- 

 tively brief (about 40 pages out of 350 in Willis's translation), and 

 that the bulk of the 106 ' exercises ' into which his work is divided is 

 devoted to comments on the older writers and discussions of the nature 

 of the process of development. 



Portraits of Harvey are by no means uncommon. The one in 

 the National Portrait Gallery, in London, is represented in Fig. 1. 

 This is usually regarded as the second-best portrait of Harvey, since 

 the one painted by Jansen, now in possession of the Koyal College of 

 Physicians, is believed to be the best one extant. Permission to repro- 

 duce the latter is not given. 



The picture in the National Gallery shows a countenance of com- 

 posed intellectual strength, with a suggestion, in the forehead and 

 outline of the face, of some of the portraits of Shakespeare. * 



The aphorism ' Omne vivum ex ovo' though not invented by 



t The earliest figures on the development of the chick are probably those 

 of Coiter, 1573. 



